Arthritis Flashcards
(15 cards)
Hallmark of arthritis
Cartilage destruction - seen as cartilage space narrowing Can be Divided into - degenerative OA - Inflammatory (RA, spondyloarthropathies, juvenile idiopathic arthritis) - crystal disposition (gout, CPPD (Calcium pyrophosphate dihydrate, Hydroxyapatite) - Haematological (haemophilia) Metabolic
OA features
Noninflammatory arthritis resulting from progressive cartilage degeneration Resultant hypertrophic change in bone Asymmetrical joint space narrowing Subchondral Sclerosis - stimulated by loss of hyaline cartilage and reactive modeling Osteophytosis Subchondral cystic changes (herniation on joint fluid in a cartilage defect) Lack of periarticular osteopenia - absence of erosions
Hip OA Imaging features XR CT MR
Radiograph: Joint-space narrowing in weight-bearing portion, osteophytes, subchondral cysts MR: Cartilage defect or thinning, labral damage, subchondral cysts ========== Femoral neck (calcar and lateral) buttressing, 92% specific Subchondral cyst formation (Egger cyst in acetabulum) Solitary acetabular cyst termed Egger cyst Subluxation femoral head 80% superolateral, 20% medial (protrusio) Often associated with underlying morphologic abnormality in young adults Femoroacetabular impingement (FAI) Developmental dysplasia of hip (DDH) MR: Bone marrow edema Volume of edema correlates with severity of hip pain, severity of radiographic OA, and number of microfractures in subchondral bone Cartilage defects are seen if outlined by fluid Cartilage in hip is thin, and capsule is tight, making cartilage more difficult to evaluate than in knee Labral tear or degeneration
Hallmark of rheumatoid arthritis
Marginally erosions (first/early) (Usually radial aspect 2nd 3rd metacarpal heads, proximal phalanges and ulnar styloid soft tissue swelling (early) defuse symmetrical joint space narrowing periarticular osteopenia joint subluxation (advanced.)
Rheumatoid arthritis in the hand and wrist. Typical joints involvement. Which are usually spared.
MCP, PIP, Carpals
Typical joints involved in rheumatoid arthritis in the feet
MTPs forefoot (20% as first site of involvements Taloalcaneonavicular Joint - mid foot
RA in the hips Imaging features
Axial migrations (Cf. Lateral or medial in OA) 2nd to Concentric cartilage loss Protrusio deformaities (3mm medial deviation of the femoral head beyond ilioischiolal line or 6mm in female
RA knees - which spaces get affected.
All three compartments. Cf. Medial tibiofemoral compartment in osteoarthritis in early disease Joint erosion is usually not a prominent manifestation on RA knee, cf. Other joints.
RA in the cervical spine
Anterior Atlantoaxial subluxation (multi direction Vertical Atlantoaxial subluxation - c1-2 facet erosion and collapse Odontoid process protrude into foramen magnum Can compress mid brain Ddx Odontoid fracture
Sacroiliitis Prevalence? Diagnosis?
Inflammatory type lower back pain. Prevalence of axial spondyloarthritis - 1% Dx of SI is 14 yrs post diagnosis in the USA DX USING ASAS CRITERIA FOR INFLAMMATORY BACK PAIN _ AGE AT ONSET
Pvns Gross pathology
Gross Pathologic & Surgical Features Intraarticular PVNS Joint filled with unclotted dark brown blood Villonodular frond-like proliferation of synovial membrane Cut surface: Yellow-brown (iron deposition) Giant cell tumor of tendon sheath Small rubbery encapsulated multinodular mass Yellow-brown in color: Deposition of lipid and hemosiderin Microscopic Features Synovial proliferation Multinucleated giant cells, hemosiderin-laden macrophages Intra- and extracellular hemosiderin; uncommonly, may contain little hemosiderin
PVNS Radiographic features
E Compare Bookmark Print Is this information what you were looking for? Imaging Location Single focus; joints, bursae, tendon sheaths Intraarticular PVNS: 80% occur in knee Morphology May be focal nodular mass May be diffuse, with villonodular proliferation of entire synovium and in all potential joint recesses MR demonstrates extent; characteristic but not pathognomonic (diagnostic in 95%) Gradient-echo imaging usually shows blooming phenomenon of hemosiderin-laden nodules Large effusion on radiograph or MR Rarely, after repeated bleeding, effusion appears dense on radiograph ± erosion; occurs in 50% ± large, well-marginated subchondral cyst Top Differential Diagnoses Nodular synovitis Gout Amyloid Hemophilic arthropathy Synovial chondromatosis Clinical Issues 5% of all primary soft tissue “tumors” Treatment Resection with synovectomy Incomplete resection has high recurrence rate Diagnostic Checklist If suspicious of PVNS, use gradient-echo sequence to elicit blooming Search carefully for all regions of involvement, including all recesses, to achieve complete resection Synonyms Pigmented villonodular synovitis (PVNS); benign synovioma; nodular tenosynovitis Giant cell tumor of tendon sheath: Pathologically identical but fully discussed in separate section Definitions Monoarticular proliferation of hemorrhagic synovium Occurs in joint, bursa, tendon sheath PVNS: Diffuse, articular form Giant cell tumor of tendon sheath: Localized, extraarticular form General Features Best diagnostic clue Radiograph: Large effusion ± associated erosions and subchondral cysts MR: Effusion with synovial proliferation, low signal on all sequences, and usually blooms on gradient-echo Location Single focus; joints, bursae, tendon sheaths Rare reports of multifocal occurrence PVNS (intraarticular): 80% occur in knee Knee > ankle > hip > shoulder > elbow Giant cell tumor of tendon sheath Hand and wrist (65-89%): Volar aspect of digits Foot and ankle Size Begins as small focal mass attached to synovium May enlarge to involve entire joint, lining entire synovial surface Morphology May be focal nodular mass May be diffuse, with villonodular proliferation of entire synovium and in all potential joint recesses In knee, can extend down popliteus tendon sheath and into posterolateral compartment, coronary recess, meniscofemoral recess, popliteal cyst, intercondylar notch, and even along collateral ligaments Imaging Recommendations Best imaging tool MR demonstrates extent of process; appearance characteristic but not pathognomonic (diagnostic in 95%) Protocol advice Gradient-echo imaging shows blooming phenomenon of hemosiderin-laden nodules in most cases Radiographic Findings Intraarticular PVNS Large effusion Rarely, after repeated bleeding, may appear dense Normal bone density Cartilage preserved until late in process Cartilage narrowing only with secondary degenerative change Osteophytes generally present at this late stage ± erosion; occurs in 50% ± large, well-marginated subchondral cyst Very rarely and late, may show dystrophic calcification Giant cell tumor of tendon sheath Soft tissue mass, generally on volar side of finger Pressure erosions of underlying bone (15%) Rare dystrophic calcifications CT Findings Nonspecific, but may be suggestive if subchondral cysts are large Effusion, soft tissue mass May have increased attenuation related to hemosiderin deposits Synovium enhances post contrast Well-defined erosions with sclerotic margins
GOUT pathophysiology
Hyperuricemia, resulting in sodium urate crystal deposition in soft tissues and joints Primary gout: Results from abnormalities in purine metabolism or from idiopathic ↓ renal excretion of urate Secondary gout: Results from increased serum uric acid levels resulting from associated disorder Neoplasm, lymphoproliferative disease End-stage renal disease (ESRD) Drugs (diuretics, ethanol, cytotoxics) Etiology Biochemical derangement: Hyperuricemia → deposition of urate crystals in soft tissue, cartilage, and bone → inflammatory response and destruction Minority of patients with elevated serum urate level develop acute attacks of gouty arthritis Tophaceous gout: Chronic phase of disease (rarely, tophi noted at time of 1st attack) Majority of cases are idiopathic; may be familial Minority of cases seen in patients with chronic disease (end-stage renal disease, psoriasis) or high rate of cellular turnover (treated widespread tumor) Associated abnormalities May cause gouty nephropathy: Crystals impair renal function (pyelonephritis, urinary obstruction)
Best clue: Dense tophi, juxtaarticular erosions with overhanging edges
Location: 1st metatarsal phalangeal (MTP) most frequent site
50% of patients have this as initial site
80-90% involve this site at some point in disease
Radiographs usually normal 1st 7-10 years of disease
Normal bone density maintained
Cartilage damage occurs only late in disease
Erosions are well circumscribed with sclerotic margins
Erosions may have overhanging edge
Tophi: Dense nodules
MR: Synovial pannus: Thickened, low T1 & T2 signal with peripheral enhancement
Adjacent soft tissue &/or bone marrow edema: Low signal T1, high signal T2
Gouty tophus has constant T1WI MR appearance: Intermediate homogeneous signal intensity
Gouty tophus appears variably on T2 & other fluid-sensitive sequences: Mixed low and high signal
Gouty tophus enhances with contrast
Diagnostic Checklist
Gout can look like anything and present anywhere in musculoskeletal system
Gout is common; maintain high index of suspicion
